Synergistic effects of repellents and attractants in potato tuber moth control

Pest management strategies aimed at reducing pesticide input often rely on behaviour-modifying stimuli to manipulate the distribution and abundance of pests and/or beneficial insects. However, the combined effect of more than one stimulus has rarely been tested. Here we show that the combination of two stimuli has a synergistic effect that controls herbivore damage and increases potato yield, despite the fact that each stimulus alone has no effect. A main potato pest in Colombia is the Guatemalan potato moth (Tecia solanivora) whose larvae specialize on potato tubers. To control this pest we tested the oviposition interference (repellence) of eight aromatic plants and the oviposition stimuli (attractiveness) of eight potato varieties. In the field we tested the effectiveness of the single and combined use of repellent and attractive stimuli on herbivore damage and tuber production of potato plants and compared the efficacy of these treatments to conventional management systems that employed insecticides. Although there was no effect of the attractive and repellent stimuli in the field when used alone, the combined use reduced the number of damaged tubers and increased the weight of undamaged tubers relative to the untreated plots, thus demonstrating a synergistic effect. Productivity in the conventionally treated plots was similar to plots treated with the combined stimuli. We demonstrate that the simultaneous use of garlic-pepper extracts and intercropping with S. tuberosum cv Roja Narino are an effective strategy for the management of T solanivora. This strategy maintains the productivity attained with conventional management practices, but without the health, environmental and ecological costs associated with the use of insecticides. (C) 2009 Gesellschaft fur Okologie. Published by Elsevier Gmbh. All rights reserved.